Catalyst for synthetic-methanol production



Patented Apr. 26, 1927.

UNITED STATES,

I 1,'62'5,92 4- PATENT OFFICE.

JOHN C. WOODRUFI' AND GROVER BLOOMFIiELlD, F TEBRE HAUTE, INDIANA, A8-

SIGNORS TO COMMERCIAL SOLVENTS CORPORATION, OF TERBE HAUTE, INDIANA,

A CORPORATION OF MARYLAND.

CAEPALYST FOB SYNTHETIC-METHANOL PRODUCTION.

No Drawing.

oxides may be employed, these substances reacting with hydrogenaccording to the following reactions 1 Carbon monoxide CO +2H Z CH OH Itis observed that when carbon dioxide is the oxide employed, one moleculeof water 213 is formed for every molecule of methanol produced. On theother hand when ure carbon monoxide is used, theoretically t ere isnothing produed by the reaction but methanol. Actually in practice purecarbon monoxide and pure carbon dioxide are both diliicult to obtaineconomically, so that the methanol synthesis is carried out by reactinga mixture of carbon monoxide and carbon dioxide with hydrogen.

In addition to the reactions producing methanol there are. in themethanol synthesis, undesirable side-reactions which cut down the yieldof the desired product. lhe prin cipal side' reaction which may occur isthe formation of methane, which is illustrated below:

When a gas mlxture comprising carbon oxides mixed with an excess ofhydrogen over 5 the amount theoretically required to roduce methanol ispassed over a catalytic su stance comprising metals or their oxides at apressure above atmospheres and at a'temperature above 250 0. there isnearly always Application filed Kay 26,

1926. Serial No. 111,884.

components. The extent of this reaction depends to some degree on spacevelocity, temperature, and pressure, but the fact remains that under theconditions outlined, carbon oxides and hydrogen react to some extent inall cases.

The substances formed by such a process depend, both as. 'to identityand as to amount, almost entirely on the nature and activity of thecatal tic substance present. The meth w auol cata yst proposed in thepast have been of two principal types :-i. .e.-

' 1. Mixtures of linely divided metals, or, whatis equivalent, mixturesof easily reducible metal oxides;

2. Mixtures of oxides of metals nonreducible, or difiicultly reducibleunder the conditions of the methanol synthesis.

In the past, also, one class ofeasily reducible metal oxides, that isthe oxides of iron, nickel, and cobalt have been described as absolutelyworthless for the production of methanol catalysts since these metalsunder normal conditions prevent the formation of methanohthereactmnproducing only methone. a

We have discovered a new type of methanol catalyst which produces ahigher yield of methanol than those formerly employed in the art, and atthe sametime produces a very pure methanol, uncontaminated bybyproducts.An additional advanta e accruing from the use of our catalysts 18 thatthe formation of methane in the process--With the consequent destructionof valuablehyew drogen-is practically eliminated.

We have now discovered a new type of valuable methonol catalyst whichcomprises three main elements-i. e.

(1) One or more non-reducible metal oxides such as zinc, magnesium,cadmium, chromium, vanadium, tungsten, etc.;

(2) One or more easily reducible metal oxides such as copper, silver,iron, nickel, cobalt, etc.;

(3) A metallic halide.

It will be observed that in our improved catalyst we may employsubstances normally deleterious to the methanol raction-namely themethanating metalsiron, nickel, or cobalt. In our improved catalystcompositions these normally deleterious substances serve advantageously,apparently exerting employ easily reducible oxides such as those ofcopper or silver which; are already known however,-=ouri imp halidesproduce ar better results than those I-lmown in the artforfotherwiseidentical catalyst mixtures. i

The precise method by which the metallic halides produce the improvementis no known to us. At least three theories may be used to account forthe phenomenon namely}?- promoter in increasing catalyst activity;

(2 The metallic halide interacts with other metallic oxides present inthe catalyst to produce oxychloride compounds which, in turn, eitherserve as catalyst promoters, or may so modify the purely physical stateof the mass as to produce a-more active catal st;

and carbon oxides during the commencement of its use as a catalyst andthe resultant finely divided metal may increase the catal st activity,or alternatively, the metallic halide mayfirst react with some othermetal producing the halide thereof, which may be reduced in the samemanner.

However, the precise explanation for the improved result attained by theaddition of metallic halides to methanol catalysts is not known andforms no part of our invention.

To produce our improved catalysts it is I not necessary that the amountof metallic halide added bear any exact weightrelation to the remainingconstituents of the catalyst, through the amount of halide added shouldpreferably be less than one chemical equivalent of the amount ofprincipal metallic oxide present in the catalyst.

As illustrative of our invention we will cite a-number of specificcatalysts. Inorder to indicate the comparative efiicacy of thesecatalysts in methanol production we have selected a standard set ofconditions of use as follows. The reported yields of condensate from themethanol reaction by use of the' following catalysts is based onthe-effect produced when'a gas mixture comprising 8% carbon dioxide, 3%of carbon monoxide and 89% hydrogen is passed through 1 liter 0*catalyst granules at a space velocity of 7 5,00,0-100,000, at a pressureof 2000 pounds,

and at a temperature of 340-=400 C In'selecting a standard set ofconditions it is our intention only to thusdisplay the catalyst efficacyand by no means to limit the "scope of ourinvention. Modification of theconditions of the reaction will, of course, modify the results, but

. ways be in the arths advantageous components of.'certainmethanolibcatalysts; In these. roved catalysts contain ng hemetallic halide acts as an ordinary 3 The metallic halide may be reducedby the high pressure contact with hydrogen nickel hydrate.

.lar results.

the I results will al-.

' proportionate to the catalyst employed. H For example, an increasedspace velocity produces'an increased hourly yield and an increase inoperating pressure has the same er fect. Likewisethe use of pure carbonmonoxideas distinguished from carbon dioxide or a rnixtureoi thetworesults in an increased'methanol percentage in the condensate,andysince" carbon monoxide seems to react more readily, an increasedcondensate volume. 7

Ezi'ample I. 8 kilograms of chromic nitrate a)3' 2 kilograms of nickelnitrate and 1.5

are dissolved in 150 liters of water, and to -hydroxide and nickelhydrate The solution is than centrifilgettifo recover the precipitatd''liydrates 'andthe resultant precipitate is thoroughly washed withwater, dried, and broken up into granules.

The resultant granules are moistened with an aqueous solution of 200grams zinc chloride and again dried, whereupon they are ready for use.

The hourly yield of condensate is about 1 liter, which analyzes about35% methanol.

Example H. 2250 grams of nickel nitrate (Nu ian-EH20) are dissolved in250 liters of water and the solution is heated to C. 7500 grams ofzincoxide is then added with stirring. To this solution there is addedsufficient ammonium hydroxide to precipitate the nickel a Theprecipitated mass is recovered by decantation and filtration, is washed,dried, and broken up into granule To this mass is added a solutioncontaining 740 grams of zinc chloride and the mass is again dried.

The hourly yield of condensate is about 1 liter and contains about 30%of methanol.

If the amount of zinc chloride used is doubled, the hourly condensatewill be increased to about 2.5 liters and the percentage ofmethanol'will be increased to about 56%.

Substitution of chemically equivalent quantities of magnesium chlorideor zinc bromide for the'zinc chloride produces simi- Ewample Ill 2250grams of cobalt nitrate (00(N0z)2 6H,O)-

are dissolved in 250 liters of water and the solution is heated to C.There is then added 7.5 kilograms of zinc oxide after which the solutionis vigorously stirred and suiti- .1480 grams zinc chloride and driedonce more.

The hourly yield of condensate is about 1.5 liters and contamsglbout 58%of methanol.

E wample IV.

If the zinc chloride .in Example III is replaced by 1300 grams ofmagnesium bromide the hourly yield of condensate and percentage yield ofmethanol is notgreatly modified.

E wample V.

7 1.5 liters and contains about 55% methanol.

Example VI. 4 kilograms chromic nitrate a)s 2 and 750 grams nickelnitrate (Ni(NO 6H O) are dissolved in 5 liters of water. 2.5 kilogramsof zinc oxide is added with stirring and the mass is heated to drynessand is then further heated till no more nitric oxide fumes are givenofit', whereby the mixture is transformed to chromic oxide, nickeloxide, and zinc oxide. The resultant mass is broken up into granules andis then moistended with a solution containing 450 grams of zincchloride. The granules are again dried and are ready for use. Ifdesired, 450 grams of dextrin or a similar agglutinating agent maybeadded with the zincchloride, whereby firmer granules are obtained ondrying.

The hourly yield of condensate is about 2.5,liters containing about 58%.methanol.

Example VII.

mic. chloride may be employed. The results w ll not be greatly varied.

Ewample VIII. 2600 grams. of zinc oxide in powdered form is nuxed bythorough sifting with 500 grams oi black copper oxide. The resultantmixture is moistened with an aqueous solu tion containing 150 gramscuprous chloride and 200 grams of dcxtriu. The resultant mass is driedand broken up into pieces whereupon it is. ready for use.

The hourly yield of condeuz'ate is about. 1.2-

liters containing about 40% of methanol.

b ow having described our invention, we (ltlilll the follmi'iug'as newand novel.

1. A methanol catalyst initially comprising a plurality of dilticultlyreducible n'letal oxides, a plurality of easily reducible metal oxides,and a metallic halide.

2. A methanol catalyst initially comprising a plurality of ditiicultlyreducible metal oxides, an easily reducible metal oxide, and a. metallichalide.

3. A methanol catalyst initially comprising a ditficultly reduciblemetal oxide, an easily reducible metal oxide, and a metallic halide.

4. A methanol catalyst initially comprising a diiiicultly reduciblemetal oxide, an easily reducible metal oxide, and a halide of one of themetals.

5. A methanol catalyst initially comprising a difficulty reducible metaloxide, an easily reducible metal oxide, and a metallic chloride.

6. A methanol catalyst initially comprising a diflicultly reduciblemetal oxide, an easily reducible metal oxide, and-a metallic halide inamount equal to one chemical equivalercilt or less of the diflicultlyreducible metal 0x1 e.

7. A. methanol catalyst initially comprisinga predominating quantity ofa difiicultly reducible metal oxide, a lesser quantity of an easilyreducible metal oxide, an an amount of a metallic halide equalt'o orless than one chemical equivalent otIthe diflicultly reducible oxide.

8. A methanol catalyst initially comprising an oxide of a second groupmetal, an easily reducible metal oxide of the eighth group, and ametallic halide.

9.-A process for the production of synthetic methanol which comprisespassing a mixture of hydrogen and carbon oxides, at a pressure in excessof 50 atmospheres and at a temperature of 350-450 C. over a catalystinitially comprising a plurality of diiiicultly reducible metal oxides,a plurality of easily reducible metal oxides, and a metallic halide.

10. A process for the production of synthetic methanol which comprisespassinga/ mixture of hydrogen and carbon oxides at a pressure in excessof 50 atmospheres and at a temperatureof 350-450 C. over a cata- 1 stinitially comprising a diflicultl reduci he metal oxide, an easilyreducib e. metal oxide, and a metallic chloride.

11.. A methanol catalyst initially comprising a plurality of difficultyreducible metal oxides, an oxide of an iron group metal and a metallichalide. o

12. A methanol catal st initially com rising a difiicultly-reduci 1emetal oxide, Iron oxide, and a metallic'halide.

13. A methanol catalyst initially comprising zinc oxide, chromium oxide,an oxide of an iron group metal, and a metallic halide.

14. A methanol catalyst initially compris 111g zinc oxide, iron oxide,and zinc chloride.

15. A methanol catalyst initially comprismg zinc oxide, chromlum oxide,an oxide of an iron group metal, and zinc chloride.

16. A process for the production of synthetic methanol whichcomprisespassing a mixture of hydrogen and carbon oxides at a pressure in excessof 50 atmospheres, and at a temperature of 350450 C. over a cataly'stinitiall comprising zinc oxide, chromium oxide, 1; e oxide of an irongroup metal, and zinc chloride. 17. A process for the production .ofsynthetic methanol which comprises passing a mixtureof. hydrogen andcarbon oxides at a pressure in excess of 50 atmospheres and at atemperature of 350-450 C. over a catalyst initially comprising zincoxide, iron oxide, and zinc chloride.

In testimony whereof we ailix our signatures.

JOHN C. WOODRUFF. GROVER BLOOMFIELD.

